Authorities in Yemen's southern city of Aden imposed a curfew on Monday after violence blamed on suspected militants killed at least 17 people, pro-government media and security sources said.The curfew will come into force at 8:00 pm (1700 GMT) and last until 5:00 am (0200 GMT), the sabanews.net website said, citing a decision taken by the Aden Security Commission.The decision comes after fierce battles on Sunday in the port of Aden that killed 17 people, among them nine members of the security forces including a colonel, the security sources said.